Fai Au could have worked anywhere. Born in Guangzhou, raised in Hong Kong and educated at Harvard, the 37-year-old architect was also a senior designer just three years ago at OMA, Rem Koolhaas' acclaimed Rotterdam-based practice. But when it came to starting his own firm, Au saw only one option: Hong Kong.

"My culture is here," he says, sitting in his North Point studio. With his shaggy hair, oversized glasses and snug collared shirt - top buttons open, revealing a gold cross around his neck - he looks more indie rock musician than architect. "Hong Kong is still a bridge between China and the rest of the world."

Churches are normally built by a church, but this one was built by a developer

Fai Au, Architect

Au is the founder of the four-person O Studio Architects, a small but ambitious practice. Espousing a holistic approach to design, O Studio has gained international attention with its most refined project to date: the Church of Seed, a chapel on Luofu Mountain, a sacred Taoist site in eastern Guangdong. The project, completed in late 2011, won the Hong Kong Institute of Architects' Medal of Excellence for projects outside Hong Kong.

"Churches are normally built by a church, but this one was built by a developer," says Au.

More specifically, a developer who wanted a Christian space that would complement the Taoist and Buddhist temples already in the area - but one that could also be used as a secular community centre.

Au's church is a curved concrete structure that has attracted international attention for its austere but graceful design. Shaped like a series of steps, mirroring the slope of the surrounding hills, the church's concrete surface is ribbed, as if moulded by bamboo. There are two sites of contemplation: the roof, with its sweeping views, and the interior, which is bathed in light from a giant cross punched into the wall.

Inspiration for the project came from Le Corbusier's Chapelle Notre-Dame-du-Haut in Ronchamp, France, which boasts a similar hilltop location and sweeping concrete form.

"I liked how Le Corbusier invited light and air into the building, how he imagined the ambience," says Au.

The Church of Seed may have got the world's attention but Au doesn't want to dwell on such esoteric projects.

One of his latest designs is for a 58,000 square metre Heineken brewery in Guangzhou, which uses white and grey tones of Guangdong village architecture into a contemporary industrial complex. He says it will be completed in the next few years.

It's an example of the creative latitude Au gained at OMA. "It's a corporate size but there's not much hierarchy. No matter if you're an intern or a senior associate, you might all work on cutting the same model. Rem Koolhaas is not a superhero lead architect who everyone follows. He's more like a critic. It's an ideal environment."

The challenge for O Studio is to maintain that philosophy as it scales up. "In Hong Kong and China, it's like a factory - you do a piece and pass it on. In Europe, architects are involved from beginning to end," says Au. "As we get bigger, I'm curious if we can keep this way of working."

This article appeared in the South China Morning Post print edition as Keeping faith in concrete ideas